Geodynamics, the developer of Australia’s first deep hot rocks energy project, aims to secure customers for its Cooper Basin site within six to 12 months, allowing it to proceed to a larger commercial plant, said chief executive Geoff Ward.

The company has spent more than $400 million since listing in 2002, including buying equipment and drilling. Its 1-megawatt Habanero pilot plant was commissioned on April 30 and has been operating in excess of expectations since, said chief executive Geoff Ward. "We're delighted by how stable and reliable" the operation has been, he said.

The geothermal plant at Innamincka in north-eastern SA taps salty water heated at 210 degrees more than 4.2 kilometres below the surface, extracting the heat to generate electricity. The cooled brine is then pumped back down a separate well where it is reheated by the hot rocks, creating an energy loop. Only two other sites now operate so-called enhanced geothermal systems, at Soulz in France and Landau in Germany.

Geodynamics will only proceed with a 5-10 megawatt commercial plant if it can secure customers. Potential clients include Santos, which operates its own gas and oil hub at Moomba, about 70 kilometres away. Beach Energy and Chevron, meanwhile, are exploring for unconventional shale gas within 5-15 kilometres of Geodynamics's wells.

GeoDynamics' competitor Petratherm seems to be losing confidence in their proposed alternative project, with the company looking to explore for shale oil in Tasmania.

After years of trying to commercialise geothermal energy in the South Australian outback, ASX listed Petratherm announced plans to diversify into shale oil and gas in Tasmania. ''This decision by Petratherm to extend into unconventional shale oil and gas exploration leverages our core areas of expertise that include basin geology and deep drilling,'' the company said.

Petratherm managing director Terry Kallis sought to reassure environmentally conscious investors that the company had not abandoned its geothermal project, which is planned to be about 75 per cent smaller than previous plans. But funding is hard to come by, and a $13 million government grant can be used only if Petratherm can raise millions of its own, a task that will be even more difficult under a lower carbon price.